CN1148108C - Variable frequency microwave heating apparatus - Google Patents
Variable frequency microwave heating apparatus Download PDFInfo
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- CN1148108C CN1148108C CNB951930621A CN95193062A CN1148108C CN 1148108 C CN1148108 C CN 1148108C CN B951930621 A CNB951930621 A CN B951930621A CN 95193062 A CN95193062 A CN 95193062A CN 1148108 C CN1148108 C CN 1148108C
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- microwave
- heating apparatus
- variable frequency
- microwave heating
- frequency microwave
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B6/00—Heating by electric, magnetic or electromagnetic fields
- H05B6/64—Heating using microwaves
- H05B6/66—Circuits
- H05B6/68—Circuits for monitoring or control
- H05B6/686—Circuits comprising a signal generator and power amplifier, e.g. using solid state oscillators
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B6/00—Heating by electric, magnetic or electromagnetic fields
- H05B6/64—Heating using microwaves
- H05B6/66—Circuits
- H05B6/68—Circuits for monitoring or control
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C65/00—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor
- B29C65/02—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure
- B29C65/14—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using wave energy, i.e. electromagnetic radiation, or particle radiation
- B29C65/1403—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using wave energy, i.e. electromagnetic radiation, or particle radiation characterised by the type of electromagnetic or particle radiation
- B29C65/1425—Microwave radiation
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C66/00—General aspects of processes or apparatus for joining preformed parts
- B29C66/90—Measuring or controlling the joining process
- B29C66/91—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C66/00—General aspects of processes or apparatus for joining preformed parts
- B29C66/90—Measuring or controlling the joining process
- B29C66/95—Measuring or controlling the joining process by measuring or controlling specific variables not covered by groups B29C66/91 - B29C66/94
- B29C66/959—Measuring or controlling the joining process by measuring or controlling specific variables not covered by groups B29C66/91 - B29C66/94 characterised by specific values or ranges of said specific variables
- B29C66/9592—Measuring or controlling the joining process by measuring or controlling specific variables not covered by groups B29C66/91 - B29C66/94 characterised by specific values or ranges of said specific variables in explicit relation to another variable, e.g. X-Y diagrams
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B40/00—Technologies aiming at improving the efficiency of home appliances, e.g. induction cooking or efficient technologies for refrigerators, freezers or dish washers
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- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Control Of High-Frequency Heating Circuits (AREA)
- Constitution Of High-Frequency Heating (AREA)
Abstract
A variable frequency microwave heating apparatus (10') designed to allow modulation of the frequency of the microwaves introduced into a multi-mode microwave cavity (32') for testing or other selected applications. The variable frequency microwave heating apparatus (10') includes a traveling wave tube (TWT) 20. The power monitor (62) receives input from the directional coupler (24') which detects the direction and amplitude of signals incident upon and reflected from the microwave cavity (32'). The power and temperature display/controller (60) further serves to control the microwave oscillator (14'), the pre-amplifier power control (18') and the TWT power supply (22'). A cooling system (66) is provided for cooling the TWT (20). A tapered waveguide coupler (68) acts as an impedance transformer.
Description
Be presented to the contract No.DE-AC-84ORZ1400 of Martin Marietta energy resource system company according to USDOE, the present invention has obtained the support of government, so government has some rights in the present invention.
The application partly discloses and requires the previous application of awaiting the reply that proposes, the No.08/306 of application on October 14th, 1994, the right of the theme that is disclosed in 305, this application discloses and requires the previous application of awaiting the reply that the proposes (No.08/221 of application on March 31st, 1994,103) theme that is disclosed in, disclose and require the previous application that the proposes (No.07/792 of application in 1991,103) theme that is disclosed in, this application has been awarded United States Patent (USP) certificate No.5 on June 14th, 1994,321,222, the theme that it discloses is that an inventor of the present invention invents at least.
Technical field
The present invention relates to microwave radiation, relate in particular to the microwave oven of ability with the frequency that optionally changes microwave source and power.
Background technology
In the microwave radiation field, well-known, microwave oven generally is to be made of fixing operating frequency.Know interaction of various materials and microwave (interaction) and frequency dependence.These interactions can comprise curing (curing) rubber and sintering (sintering) pottery.Therefore, wish to have the microwave oven that on wide frequency range, to work.
The bandwidth of most of microwave sources is very narrow, and this is because they use resonant cavity.The microwave oven of making for family expenses is provided with magnetron, and it is operated on the 2.45GHz, and this is to add the effective frequency of hot water.Because the microwave of 2.45GHz and the coupling ability of water, these microwave ovens are used for cooked food, drying and other purpose, and the main material that is wherein acted on is a water.Yet well-known, the frequency in this scope is not suitable for all occasions, and for example the material of heating plasma, sintering such as silicon etc. and preparation are such as diaphragms such as diamond diaphragms.
Making the important implication of the inswept relative broad range of frequency by mode swing (mode stirring) method is with microwave power medicine equipment or contaminated refuse to be carried out disinfection.Use " dead band " that may not receive enough power that has determined to eliminate in the chamber like this, thoroughly to carry out disinfection.Electronic frequency scanning can be carried out with higher speed, thereby has produced uniform power density on the more consistent time in whole furnace chamber.Desired frequency scanning can realize by using various microwave electron equipment.For example, spiral travelling wave tube (TWT) is with (2.45 ± 0.05GHz) compare the bandwidth (for example 2 to 8GHz) that can make scanning cover broad such as voltage tunable magnetron.As hereinafter disclosing, miscellaneous equipment has other characteristic bandwidth.
Again, the microwave oven of the fixed-frequency of known general family use has cold spot and focus.This phenomenon is to be caused by the ratio of wavelength to the microwave cavity size.The microwave of lower frequency introduced in the less chamber, can be produced standing wave, so microwave power not that the institute that is full of equably has living space in the chamber in that unaffected zone is heating not.Under opposite extreme situations, in fact furnace chamber becomes " single mode " chamber.
Under the mode swing, carried out repaying examination, perhaps made microwave " bundle " deflection randomly,, thereby made microwave radiation be full of cavity with elimination standing wave mode.It is a kind of that to repay examination be the fan blade that increases rotation in the wave beam import department in chamber.
The another kind of method that overcomes the standing wave adverse effect is deliberately to produce standing wave in single mode chamber, can be placed on workpiece on the have peak power position of (focus).Therefore, only standing internal wave the most concentrated part in chamber can be used.
Though also do not know the reason that it is correct, show that the various materials of sintering can improve on high frequency.Yet prior art is difficult to carry out the series of identical swing experiment that only changes frequency.This major part is that different furnace chambers is interior to be caused because each microwave source is connected to.As everyone knows, the geometry of furnace chamber is the parameter that must consider in this experiment.
In some works, reported and introduced the stove of gyrotron oscillator with the 28GHz microwave of generation fixed-frequency.The gyrotron stove can be than those microwave ovens that are provided with the 2.45GHz magnetron some material of sintering more effectively.The gyrotron stove is having special application aspect the materials such as sintered ceramic.Yet 28GHz is not the effective frequency of sintering all material.Require to determine the most effective frequency is added on the specified material in the stove in the chamber that has selected structure.
The most effective processing frequency can change with the material of appointment when heat treated.When material changes state, also may require to change frequency.Therefore, can require it in heating process, to have the ability that changes frequency, allow tester to begin, along with the rising of temperature, change frequency, then to keep good coupling with a frequency heated sample.When also may be required in the heating synthetic material, change material and come effectively different frequency to be worked.
The equipment of also having produced other changes the parameter of the heating process of selected materials.Typical technology is the equipment that is disclosed in the following United States Patent (USP) in the prior art:
Patent No. inventor's date of declaration
3,611,135 D.L.Margerum 1971.10.5
4,144,468 G.Mourier 1979.3.13
4,196,332 A.Mackay B wait 1980.4.1
1982.7.20 such as 4,340,796 M.Yamaguchi
1983.11.15 such as 4,415,789 T.Nobue
1985.3.12 such as 4,504,718 H.Okatsuka
4,593,167 O.K.Nilssen 1986.6.3
4,777,336 J.Asmussen 1988.10.11
4,825,028 P.H.Smith 1989.4.25
1989.6.27 such as 4,843,202 P.H.Smith
1989.9.12 such as 4,866,344 R.I.Ross
1990.7.3 such as 4,939,331 B.Berggren
Being published on the microwave power periodicals of 1979 14 (1) phases, work such as Mackay B., name is called the theme that MacKay exists and disclosed in ' 332 further is discussed in " frequency sensitivity of microwave oven (agile) source " article.Yet,, outside 103, do not disclose microwave oven with wide frequency range except the above-mentioned application No.07/792 that awaits the reply jointly.
An obstacle that uses wide frequency range is to be difficult to realize efficiently microwave is coupled to the multimode chamber of applying ointment or plaster, especially when this coupling device comprises dielectric window.
Therefore, one object of the present invention is to provide a kind of microwave heating equipment, and it can be worked on wide frequency range.
Another object of the present invention is to provide a kind of microwave heating equipment that can work on wide frequency range, wherein this microwave source can exchange with the microwave source with other frequency range.
A further object of the present invention is to provide a kind of like this microwave heating equipment, wherein, can be set to two or more microwave sources in the system with parallel mode.
Another purpose of the present invention is to provide a kind of microwave heating equipment that comprises a plurality of microwave sources that be arranged in parallel, and wherein, use can be selected and replace to microwave source.
Another purpose of the present invention is to provide a kind of microwave heating equipment with a plurality of microwave sources, and each microwave source is by same signal generator and power supply control.
Another purpose of the present invention is to provide a kind of microwave heating equipment, and frequency transfers the shortcoming can be as the form of mode swing (mode stirring), to produce more uniform power distribution in multimode chamber and the load that sets within it.
Summary of the invention
The present invention also will realize other purpose and advantage, it be designed to modulate be incorporated into be used to test or the furnace chamber of other selected application in microwave frequency.Some available processing comprise heat treatment, sterilization, sintering, plasma treatment, mineral processing, polymerization, etching and preparation film.
The invention provides a kind of microwave signal generator, be used to produce the low power microwave signal, be input in the microwave amplifier.Signal generator in the preferred embodiment can an inswept specified scope frequency, with pulse mode work, the frequency of modulated microwave signal, and produce the waveform of various complexity.The microwave signal generator of preferred embodiment can utilize inner pulse generator to be operated in pulse mode, perhaps can obtain pulse from the outside.Be provided with an inner modulation device to carry out wide-band modulation.The inner modulation device can be operated in amplitude modulation (AM) pattern or frequency modulation (FM) pattern.
Voltage controller is used for the amplitude of modulated microwave voltage controlled oscillator.Microwave voltage controlled oscillator can be used for substituting microwave signal generator, to improve the frequency and the amplitude of the microwave that produces.
Can provide first amplifier, with the amplitude of the signal that amplifies the output of microwave signal generator or microwave voltage controlled oscillator.First amplifier of preferred embodiment is voltage-controlled, and therefore, its gain can be regulated, and the operator can select the amplitude exported.
Second amplifier is provided, handles the signal of first amplifier output, perhaps when handling from the signal of microwave signal generator or microwave voltage controlled oscillator output during first amplifier.Second amplifier is to furnace chamber output high-power microwave signal, and makes workpiece be subjected to microwave radiation.In preferred embodiment, second amplifier can be spiral travelling wave tube (TWT), coupling cavity TWT, annular TWT, encircle one of excellent TWT, klystron, twystron or gyrotron.These devices comprise the inside cooling device that is designed to the heat that augmented diffuser gathers in normal work period.
In another embodiment of the present invention, the oscillator and first and second amplifiers can replace with the coaxial magnetron of frequency sensitivity, and its frequency can be manually, machinery or electric tuning.
One power supply is provided, is used for the work of second amplifier.In preferred embodiment, the DC power supply that power supply is made up of the spiral power supply of accurate voltage stabilizing and the high voltage source of no voltage-stabilizing controller.
One directed coupler is provided, is used for the direction of detection signal and further controls this signal according to detected direction.The signal that receives from microwave source is delivered to microwave cavity.Deliver in the reflection power load from the signal that the direction of microwave cavity receives.Therefore directional coupler provides a kind of means, utilizes this means, and reflection power is left microwave source, avoids not by the workpiece power absorbed with the protection microwave source.The directional coupler of preferred embodiment is water-cooled, the heat that the power reflection of coming with diffusion power delivery of microwave source and microwave cavity is gathered.
First wattmeter is provided, is used to measure the power of supplying with microwave cavity.Second wattmeter that first wattmeter is used for being arranged to measure with the position power that comes from the microwave cavity reflection is connected, with the efficient that monitors microwave cavity and guarantee in the reflection power load this reflection power of consumption rather than consumed by second amplifier.
The reflection power load can also be used for thus, all signals of second amplifier being delivered to the function that the reflection power load comes test macro by remove all workpiece from furnace chamber.The power ratio of power that can receive the reflection power load and the output of second amplifier, to determine the loss of system.
The amplitude of the second wattmeter detection of reflected power.This amplitude can be used to determine be incorporated into the efficient of the real-time frequency of the microwave in the microwave cavity.Because the higher absorptivity of selected workpiece is so lower reflection power is represented more effective operating frequency.
The transition (tapered transition) that convergent can be provided can be coupled to the wide-band microwave energy in the microwave cavity with this convergent transition to raise the efficiency.As the impedance transducer between transmission line and the microwave cavity, this transition has improved the power percentage that is coupled in the chamber it.In addition, for being coupled to application in the chamber of active gases to microwave energy, this convergent transition provides the method for a kind of minimizing power density of microwave energy between the interface between window and the active gases, thereby prevents to form plasma discharge at input window.
Summary of drawings
According to the following detailed description of the present invention and accompanying drawing, These characteristics of the present invention will be easier to understand.
Fig. 1 is the schematic diagram of the preferred embodiment of variable frequency microwave furnace system of the present invention;
Fig. 2 is the schematic diagram of another preferred embodiment of variable frequency microwave furnace system of the present invention;
Fig. 3 is the perspective view of travelling wave tube, and part has been done to analyse and observe, and it forms variable frequency microwave furnace system of the present invention;
Fig. 4 is a schematic diagram of forming the travelling wave tube of variable frequency microwave furnace system of the present invention;
Fig. 5 is the end-view of travelling wave tube, has done to analyse and observe, and it forms variable frequency microwave furnace system of the present invention;
Fig. 6 is the schematic diagram of another preferred embodiment of variable frequency microwave heating apparatus of the present invention;
Fig. 7 is the view of convergent waveguide applicator of the present invention, shows its inlet;
Fig. 8 is the end-view of the convergent waveguide applicator of Fig. 7, shows its outlet;
Fig. 9 is the bottom surface sections view of convergent waveguide along the 9-9 line of Fig. 7;
Figure 10 is another embodiment end-view of convergent waveguide applicator, and it further comprises dielectric window, and shows its outlet;
Figure 11 is the bottom sectional view of convergent waveguide along the 11-11 line of Figure 10;
Figure 12 is the end-view of another embodiment of convergent waveguide, shows its outlet, and wherein inner wall limit is that step is dwindled;
Figure 13 is the bottom sectional view of convergent waveguide along the 13-13 line of Figure 12;
Figure 14 is the end-view of another embodiment of convergent waveguide applicator, shows its outlet, and wherein inner wall limit is that step is dwindled, and has comprised dielectric window;
Figure 15 is the bottom sectional view of convergent waveguide along the 15-15 line of Figure 14;
Figure 16 shows the front view of the observation panel that is used to observe the activity in the microwave cavity used according to the present invention;
Figure 17 is the cross-sectional end view of the observation panel of Figure 16 along the 17-17 line;
Figure 17 A is the part enlarged drawing of the observation panel of Figure 17, to clearly show that the sealing mechanism of the door that seals the used microwave cavity of the present invention;
Figure 18 shows the schematic diagram of another preferred embodiment of variable frequency microwave heating apparatus of the present invention;
Figure 19 is the curve chart of the mode density in a used rectangle microwave chamber of the present invention to frequency;
Figure 20 A-D shows the theoretical model of the used microwave cavity of several characteristics according to the present invention and the distribute power in first microwave source with figure;
Figure 21 A-F shows the theoretical model of the used microwave cavity of several characteristics according to the present invention and the distribute power in second microwave source with figure.
Embodiments of the present invention
Variable frequency microwave heating apparatus with the various characteristics of the present invention generally illustrates with 10 in the drawings.Microwave heating equipment 10 is designed to modulate and is incorporated in the microwave cavity to test or to carry out the frequency of the microwave of other selected application.This modulation for test process to determine that it is useful that certain material is handled the most effective frequency.Frequency modulation(FM) is the same with the mode swing that produces uniform power distribution more in less furnace chamber also to be useful.
Frequency modulation(FM) test is useful when the effective sintering frequency of definite selected materials not only, and also is useful in the most effective sintering frequency of the various states of definite selected materials.In an identical manner, also be useful aspect the material that frequency modulation(FM) changes at treatment state, wherein every kind of material state all more effectively is connected on the frequency of the frequency shift of other state.And frequency modulation(FM) also is useful when handling synthetic material, and wherein every kind of composition is connected on the frequency different with other composition.
Fig. 1 schematically shows the preferred embodiment of variable frequency microwave heating apparatus of the present invention, and wherein selected workpiece 36 is just pending.The processing that can carry out comprises heat treated, sterilization, sintering, plasma treatment, ore processing, polymerization, etching and preparation film etc., but is not limited to these.Should be appreciated that term used in this announcement " workpiece " relates to the combination of selected material or material.Term " workpiece " may further include the combination of selected material like this or material, and wherein at least a material will pass through the variation of at least a state, therefore, and at the unlikely a kind of state of material preset time.
One microwave voltage controlled oscillator 14 is provided, is used to produce the low power microwave signal, be input in the microwave oven 32.Complicated wave form generator 12 provides control voltage to voltage controlled oscillator 14, makes voltage controlled oscillator scanning specified frequency scope, and it is operated in pulse mode, the frequency of modulated microwave signal, and produce various complicated wave forms.
The complicated wave form generator 12 of preferred embodiment can be operated in pulse mode with internal pulses, perhaps can obtain pulse from the outside.The inner modulation device is set to carry out wide-band modulation.The inner modulation device can be with AM pattern or the work of FM pattern.
Microwave voltage controlled oscillator 14 produces frequency and is added to the microwave signal that the voltage on the voltage controlled oscillator 14 is determined by waveform generator 12.With selected materials can be effectively with the characteristic frequency coupling and require high voltage the same, can require the modulated microwave frequency, although second kind of material can more effectively be coupled with different frequency with under low or high voltage.Therefore, microwave voltage controlled oscillator 14 can use with complicated wave form generator 12, to revise the frequency of the microwave that produces.
Can see that the combination that frequency and power stage are possible is countless.And, this frequency and amplitude modulation(PAM) ability having been arranged, can see, can replace the processing that realizes workpiece 36 by frequency and the amplitude that makes microwave, to reach maximum treatment effeciency.Modulation can be carried out with such speed, so that workpiece 36 can not detect, but still can produce maximum treatment effeciency to each material and materials behavior.
First amplifier can be provided, amplify the power of the signal of microwave voltage controlled oscillator 14 outputs.First amplifier 18 of this preferred embodiment is voltage-controlled, so its gain is adjustable, so output amplitude can be selected by the operator.At variable frequency microwave heating apparatus 10 duration of works, the operator can regulate first amplifier 18 simultaneously, so amplitude that can corresponding adjusting microwave.The control voltage of first amplifier 18 can also be provided by complicated wave form generator 12, can be with the amplitude of desired mode modulation signal output.
TWT20 is a kind of linear beams device, and its amplifies and the output device signal of selected frequency and waveform to some extent.TWT20 has the ability of amplifying institute's selected frequency or waveform in the structure institute's restricted portion of TWT20 or bandwidth.Especially, the physical geometry of TWT has been placed restrictions on frequency range, so when reaching in limited time high, will run into offseting signal, second ripple occurs.
To introduce the frequency that the TWT20 in the ad hoc structure can provide in order reaching to be higher than or to be lower than, to change internal geometry, the especially spacing of spiral 40 of TWT20.Among the TWT20 that mentions in the back, can define a new frequency range.Therefore will see that the change of TST20 structure is possible, so can reach wider frequency.So far, TWT20 of the present invention is designed to selectively remove from variable frequency microwave heating apparatus 10, and exchanges with other this TWT20.Therefore, single microwave voltage controlled oscillator 14, microwave oven 32 and microwave cavity 34 can use with various TWT20, so, can only carry out series of identical test to microwave frequency as primary variables.A TWT20 can limit the frequency range of 4GHz to 8GHz, and another TWT20 ' defines the frequency range of 8GHz to 16GHz.Another TWT20 " can limit the 3rd frequency range.TWT20 and TWT20 ' are exchanged the total size that defines from 4GHz to 16GHz.The TWT20 of the scope of a kind of 4GHz to 8GHz of qualification is the Model T-1096G/H Band Helix TWT that Microwave Laboratories (microwave test chamber) company makes.The technical specification of the Model T-1096 that in table 1, lists.
As mentioned above, travelling wave tube 20 is a kind of linear beams devices, and its characteristics are that row moves electric field and vertically obtains energy along the path of electron beam continuously.As shown in Figure 3 and Figure 4, typical TWT20 is connected on first end 46 of single-wire helix 40 by electron gun structure 44 to constitute.Rifle assembly 44 produces the electron beam that focuses on, and directly passes the central authorities of taenidium 40.The carbon attenuator 50 that forms whole convergent with taenidium 40 is used as directional coupler, prevents to turn back to from path the reflection of the input of pipe.Radio frequency input and output winding 52,54 is separately positioned on the negative electrode and the collecting terminal of taenidium 40.
The technical specification of table 1 T-1 096G/H Band Helix TWT
Radiofrequency characteristics
Minimum value
Maximum
Representative value
Unit
Power is exported 63.0 65.0 63.5 dbm
Frequency range 4.0 8.0 Ghz
Harmonic content--3.0-6.0 dbc
Gain 25.0 37.0 30.0 db during nominal power
Electrical quantity
Taenidium voltage-8.0-9.0-8.4 kV
Anode voltage (WRTC) 0.0+9.0-kV
Catcher voltage (WRTC)+6.2+6.8+6.5 kV
Silk thread voltage (WRTC) 12.4 13.2 12.8 V
Solenoid voltage 35.0 57.0 48.0 V
Vac-Ion voltage+3.5+5.0+3.5 kV
Taenidium electric current-25.0 15.0 mA
Anode current-5.0-mA
Collector electric current 0.9 1.8 1.2 A
Silk thread electric current 1.2 2.0 1.4 A
Solenoid current 21.0 26.0 25.0 A
Vac-Ion electric current-0.01-mA
Best power 10.7 9.2 kW
Be positioned at second end 48 of taenidium 40 by the collector 56 of positive charge.Collector 56 provides TWT20 the energy of work.Electron beam focuses on and sealing magnet 58 is trapped among outside the black box of TWT20.
The electronics of advancing on the axle of taenidium 40 interacts with the rf wave of propagating along taenidium 40, and energy is transferred on the rf wave from electron beam.This interaction is carried out and constantly accumulation continuously, has increased its amplitude in radiofrequency signal when taenidium 40 is propagated.
And the retainer of present embodiment 42 is made by beryllium oxide.Although known beryllium oxide is an electrical insulator, it still is splendid heat carrier.Copper cash limits the plane cross section and contact efficiently with the plane 43 of retainer 42 basically and spread up hill and dale and is transferred on the copper cash hotly, therefore, for the inside of spiral TWT20 provides cooling device 38, has prolonged the life-span of spiral TWT20.
Be provided with power supply 22, be used for the work of second amplifier 20.Though do not draw separately in the drawings, the serve as reasons DC power supply of collector high voltage source composition of the cathode power of accurate voltage stabilizing and no voltage stabilizing of preferable power supply 22.The output voltage stabilizing of cathode power realizes by the electron tube voltage stabilizing circuit that uses tetrode.A kind of such electron tube is an Eimac 4PR400A electron tube.Voltage stabilizing to collector power supply and the former power supply of negative electrode is to use the electromechanical pressurizer.The collector power supply of this preferred embodiment is provided with two switchboards, is used to select output area.Be used for providing the typical power supply 22 of electric power to be general Voltronics type BRE-15-140-ML high voltage source to second amplifier.In table 2, listed the technical indicator of this general Voltronics power supply.
The power technology index of the general voltronics Model of table two BRE-15-140-ML power supply
The taenidium power supply
Output voltage 500V-15KVDC
Output current 140mADC
The output of polarity negative pole
Ripple .01%rms 15KVDC, 140mADC
Voltage stabilizing, load .01% (from zero load to fully loaded), maximum output
Voltage stabilizing, circuit+0.1%, the 190-230VAC line voltage distribution,
Maximum output
Catcher voltage
Output voltage and electric current
I type (flat connection) 0-5KV, 4000mA
II type (series connection) 0-10KV, 2000mA
The output of polarity positive polarity, negative pole is connected to the taenidium power supply
Ripple 3%rms, 10KVDC, 2000mA
Voltage stabilizing, load+2% (from zero load to fully loaded), maximum output
Voltage stabilizing, circuit+2%, the 190-230VAC line voltage distribution,
Maximum output
Safety circuit(being connected across on the collector power supply)
System
Input voltage 190-230VAC, phase and phase, 3 phases,
60Hz，30KVA
Electric power connects 5 end connecting plates (3 phase center-point earth)
An out connector 10-32 post, be used for collector,
Negative electrode and taenidium
As shown in Figure 2, variable frequency microwave heating apparatus 10 can be without microwave voltage controlled oscillator 14 and 18 work of first amplifier.In this embodiment, produce selected signal with microwave signal generator 12 separately, and the directly output without modulation.Model 6724 signal generators that a kind of this class microwave signal generator 12 is made for Wiltron.In the present embodiment, in the power supply 22 of second amplifier 20, carry out amplitude modulation(PAM).
Referring to Fig. 1 and Fig. 2, a directed coupler 24 is provided, be used for the direction of detection signal, and further signal carried out orientation according to detected direction.Directional coupler 24 be arranged on second amplifier 20 collecting terminal near.The signal that receives from second amplifier 20 is delivered in the microwave cavity 32.The signal that receives from microwave cavity 32 directions is delivered to reflection power load 28.Therefore, directional coupler 24 provides means, that is, and and reflected signal-promptly, the power in the source of returning 20 that workpiece 36 does not absorb-leave second amplifier 20 is not subjected to the influence of workpiece 36 unabsorbed power to protect second amplifier 20.The reflection power load 28 of the good embodiment of this reality is water-cooled, the heat of gathering with the power that diffuses through microwave reflection chamber 32.
The signal of second amplifier, 20 outputs is introduced in the microwave cavity 34, is absorbed by selected workpiece 36.Generally, workpiece 36 can not absorb the signal of introducing fully, and therefore the signal of introducing is reflected and returns second amplifier 20, and does not have other path.
Reflected signal arrives directional coupler 24, is diverted second wattmeter 26, at last to reflection power load 28.As mentioned above, in reflection power load 28, consume reflection power, to protect the life-span of second amplifier 20.Also can remove all workpiece, reflection power load 28 is used for the function of test macro, thus whole load be linked in the reflection power load 28 from second amplifier 20 from furnace chamber 34.The power ratio that the power that can receive reflection power load 28 and second amplifier 20 send, with the loss of definite system.
The size of second wattmeter, 26 detection of reflected power.This value can be used to determine to be incorporated into the efficient of real-time frequency of the microwave of microwave cavity 34.Low reflection power is represented the efficiency operation frequency, and this is because selected workpiece 36 has higher absorptivity.
Person skilled in the art can recognize the advantage of having pointed out that 10 pairs of prior arts of variable frequency microwave heating apparatus provide from above-mentioned description.Specifically, microwave heating equipment 10 of the present invention provides a kind of adjusting to be incorporated in the chamber 34 means with the frequency of the microwaves such as processing that carry out sintering or other requirement.As can be seen, microwave heating equipment 10 of the present invention is useful at the test selected materials during with respect to the treatment characteristic of microwave frequency.This test can design the microwave oven 32 that has microwave source, to produce the microwave of determining frequency.
It can also be seen that microwave heating equipment 10 of the present invention also can be used as microwave can be with the tool of production of different materials or materials behavior variation.Can carry out frequency modulation(FM) at the microwave heating equipment duration of work, to adapt to various materials and materials behavior.And frequency modulation(FM) ability of the present invention can be used as the method for mode swing, to produce more uniform power distribution in less microwave cavity 34.
The various tests of carrying out have on stream shown the efficient of variable frequency microwave heating apparatus 10 of the present invention.Two embodiment that tested are described below.Yet the inventor limits the invention to these embodiment.
In the embodiment that first was tested, constitute the microwave oven 32 of the 2.5KW that is suitable for sintering, heat treatment and other high-temperature process.Voltage controlled oscillator 14 (model VC0 100-0243 is made by Delphi company) is provided from 4 to 8Ghz continually varying low power microwave signals by 0 to 15V control signal.Solid-state prime amplifier 18 (model NHI 4080MW-2 is made by National Hybrid company) with variable gain selection provides the signal that amplifies voltage controlled oscillator 14 changeably.
One dual directional coupler 24 (model R202-5N is made by microwave engineering company) is set, applies microwave power by this dual directional coupler.Microwave power is input to diameter to be about 12 inches to be about is that 34 underexcitations go out multiple microwave mode at random in the chamber in 9 inches the multimode 34.Measure forward and reflection power level continuously with two wattmeters (model HP436A is made by Hewlett Packard company).
Verifiedly can both carry out effective microwave heating to carborundum and boron carbide ceramics body.Under each situation, the energy regulating frequency is so that the reflection power minimum of the actual loading in the chamber 34 heats pottery apace.Here do not need to adjust the size in chamber 34 or motivate specific mode, heat with maximal efficiency ground.
In second embodiment that tested, be the microwave oven that 2 to 8GHz travelling wave tube constitutes the 300W that is applicable to plasma treatment, sterilization and food processing research etc. at least with the multimode chamber 34 of conventional microwave oven and air cooled bandwidth.
To comprising water, puffed rice and mixing Co, Cr or if the various samples such as aluminium pottery of V oxide carry out evidence and regulate microwave frequency the reflection power minimum can be heated efficiently.Shown result is, when frequency continuously during inswept bandwidth of operation, reflection power is extremely low, and the efficiency of heating surface of sample and its location independent in chamber 34.
Variable frequency microwave heating apparatus 10 is carried out this test to be comprised epoxy resin (that is, the ERL-2258 resin of being made by Union Carbide, and the M-phenylenediamine curing agent of being made by Dupont) sample is cured.According to the explanation biased sample of manufacturer, pour in the glass plate of 4 inches of diameters.Frequency with fixing 6GHz heats a sample, and heats another sample according to the present invention with frequency is scanned for 5000 times from 4.5 to 7.5MHz per seconds.The sample of fixed frequency obtains uneven heating and heat escape greatly.The sample of scanning frequency is solidified equably, does not have the local phenomenon of crossing heating, thereby the value of proof frequency scanning is to produce more uniform power distribution in microwave cavity 34.
That shown in Figure 6 is another embodiment of variable frequency microwave heating apparatus 10 '.In this embodiment, the output of the demonstration of power and temperature and controller 60 received power monitors 62 and temperature sensor 64.Power monitor 62 receives the input of directional couplers 24 ', it as with previous embodiment in reflex to the identical basic role of wattmeter 26,30.Power and temperature show and controller 60 also is used for controlled microwave oscillator 14 ', the control 18 ' of preamplifier device power and TWT power supply 22 '.Be provided with a cooling system 66, be used for cooling off TWT20 at least at its duration of work.
The waveguide coupler 68 of one convergent can be provided,, the wide-band microwave energy be coupled in the microwave cavity with this convergent waveguide coupler 68 to raise the efficiency.As the transmission line of directional coupler 24 ' and the impedance transducer between the microwave cavity 32 ', this transition has increased the power percentage that is coupled in the microwave cavity 32 ' it.In addition, for being coupled to application in the microwave cavity 32 ' of active gases to microwave energy, this convergent waveguide 68 provides the method for a kind of minimizing power density of microwave energy between the interface between window and the active gases, thereby prevents to form plasma discharge at input window.
Shown in Fig. 7-9 is convergent waveguide applicator 68A.Fig. 7 shows the end-view of inlet 72.Fig. 8 shows the end-view of outlet 74.Fig. 9 is the cross-sectional view of waveguide applicator 68A, illustrates in greater detail the inwall 70 of convergent therein.As can be seen, the embodiment of waveguide applicator 68A defines inwall 70 from these figure, and it exports 74 greater than inlet 72 from entering the mouth 72 to the smooth taper of outlet 74 formation.Along on the arbitrary given cross section of its length, the inwall 70 of waveguide applicator 68A is generally the opening of rectangle, and jut 76 extends from its arbitrary part.Jut 76 also defines rectangular cross section.As shown in these figures, these juts define the proportional smooth taper of taper with the inwall 70 of waveguide 68A.The body of waveguide applicator 68A defines an end plate 78, is used for waveguide applicator 68A is fixed to microwave heating equipment 10.
In fact, have been found that with the waveguide applicator 68A shown in Fig. 7-9 and realized in whole useful microwave cavity scope, recording the free space voltage standing wave ratio that is about 2: 1.
Variable frequency microwave heating apparatus 10 has been built into microwave laboratory company and has made, 4-8GHz, model is that the TWT source of T-1096 is tested, and added the convergent waveguide applicator 68A shown in Fig. 7-9.Also used tubular multimode microwave cavity 34.(1993, the Amer.Cer.Soc. spring session Cincinnati) was discussed the result who tests to people such as R.A.Rudder, this article is quoted at this, with for referencial use " the microwave excited plasma by water-ethanol solution carries out diamond CVD ".In these tests, verified, the microwave heating equipment 10 that comprises waveguide applicator 68A of the present invention produces the highdensity local plasma that can move and can control by regulating frequency.Intensive plasma remains on the little degree to 100W of forward power.The reflection power minimum of all frequencies on the bandwidth of 4-8GHz.
Above-mentioned microwave source 12 comprises a spiral TWT amplifier.Yet should be appreciated that according to other aspects of the invention, also can use many other microwave sources 12.Following table 3 has provided the general characteristic of some other microwave sources 12 that are suitable for.
The characteristic of some microwave sources that are suitable for of table three
| Source Type | Frequency range (GHz) | Bandwidth (%) | Maximum output (kW) | Average output power (kW) | Gross efficiency (%) |
| Annular TWT | .5-20 | 5-15 | 1-20 | .05-.6 | 30-45 |
| Encircle excellent TWT | .5-20 | 10-20 | 3-30 | .08-.9 | 30-45 |
| Klystron | .5-70 | 5-8 | 100-8000 | 1-5000 | 40-70 |
| Intersect an Amp | .5-20 | 15-40 | 100-3000 | 1-300 | 30-50 |
Therefore spiral TWT in the above-described embodiments needs extra power and support equipment by liquid cools.For in laboratory scale experiment, air cooling but variable frequency microwave heating apparatus 10 is that spiral TWT of air cooling (for example, T-1067 type) and convergent waveguide applicator 68A of the present invention with microwave laboratory company makes.Use 13 * 13 * 10 inches rectangle microwave chamber 34, in this chamber, can both be coupled effectively at microwave power on 2.5 to 7.5MHz frequency ranges.Will be appreciated that this scope has almost covered two frequencys multiplication.With heat-sensitive paper test proof, frequency scanning produces uniform power density in whole chamber 34 be high efficiency.
The microwave cavity 34 of present embodiment carried out the similar test carried out with above-mentioned cured epoxy resin (the ERL-2258 resin of making by Union Carbide, and the M-phenylenediamine curing agent of making by Dupont).In these tests, frequency range and sweep speed are all reduced, swing necessary minimum zone to determine suitable mode.Simultaneously, sample volume is increased to the disk of 6 inches of diameters.From these results, can draw significantly,, especially high-termal conductivity is arranged in some samples, help the sample that makes less spatial variations average for those even 20% bandwidth also is enough to carry out uniform microwave heating.
As mentioned above, microwave heating equipment 10 of the present invention is equipped with more than more than one microwave source 12.For this scope, also following microwave heating equipment 10 has further been done improvement, increased the 2nd TWT (the T-1068 type of microwave laboratory company) and the second convergent microwave applicator 68A, made the bandwidth of stove 32 be about 2.5, perhaps near third octave to 17.5Ghz.Not should be appreciated that and should be interpreted as above-mentioned example microwave heating equipment 10 of the present invention is restricted to two microwave sources 12.On the contrary, should be appreciated that any a plurality of microwave sources 12 and waveguide applicator 68 can make up with a microwave cavity 34 according to the present invention.
Figure 10 and 11 shows another embodiment of waveguide applicator 68B, wherein is provided with window 80, is used for a kind of like this environment, that is, the pressure in the microwave cavity 34 is different with pressure on every side, and/or what use when microwave heating treatment is the gas of air.The inlet 72 of this embodiment is similar to last embodiment, and therefore, Fig. 7 represents the inlet 72 of the embodiment shown in Figure 10 and 11.Window 80 is essentially dielectric, is able to take positive and negative pressure.The inwall 70 of the present embodiment of waveguide applicator 68B ends at the non-tapered end 82 of tubular of outlet 74.Jut 76 ends at inwall 70 slope variation places.End plate 78 forms groove 84, to hold dielectric window 80.Form being fixed on the end plate 78 of centralized positioning opening 88, and be fixed at least on the outer rim of dielectric window 80, to guarantee the position of window 80 with respect to waveguide 68B.Be provided with seal 90 between window 80 and the waveguide 68B and between window 80 and the fixed head 85, flowing to the outside from microwave cavity 34 by waveguide applicator 68B to prevent liquid.
Embodiment shown in Fig. 7-9 is the same, can be implemented on the microwave cavity 34 whole useful frequency ranges with the waveguide applicator 38B of Figure 10-11 and records the free space VSWR that is about 2: 1.
Person skilled in the art should be appreciated that many traditional technology can be used for convergent waveguide transition 58 is connected in the furnace chamber 34 and dielectric window 80 and are closed in the waveguide 68.Should also be understood that this situation to occur, promptly must cool off dielectric window 80 or waveguide 68 with similar fluid such as suitable air-flow, liquid coolant flow.
Person skilled in the art it is also understood that the coupling that provides carinate broadband waveguide (for example WRD350 type) best is provided the convergent ridge, if use non-rib waveguide between microwave source 12 and convergent waveguide transition 68, does not then need.
Figure 12 and 13 illustrates another embodiment of waveguide applicator 68C of the present invention, and represents to enter the mouth 72 with Fig. 7 again.As shown in the figure, in the present embodiment, jut 76 is opposite with the smooth taper of Fig. 8 and 9, forms the step taper.Therefore, form series of rectangular jut 76A, the length of the jut that each is continuous increases to outlet 74 directions, relatively the length between the projection 76A along with relative projection 76A each continuously to increasing.Opposite with the smooth taper of previous embodiment, the projection 76A of present embodiment has changed size on limited amount discrete location.The free space VSWR that is included in the present embodiment is favourable.
Further improvement to the embodiment shown in Figure 12 and 13 is the embodiment shown in Figure 14 and 15.This embodiment further comprises dielectric window 80, to fix with the embodiment similar forms of Figure 10 and 11.
Should be appreciated that when the operation microwave equipment, during especially with high power operation, must carry out suitable sealing or shielding, to prevent undesirable microwave radiation leakage to equipment.Should also be understood that the increase along with useful frequency range, it is difficult more that shielding becomes.For example, the common microwave stove that is operated on the 2.45Ghz fixed frequency just can make leakage minimum by using to the invalid resonant mechanical flow plug of high frequency.Because microwave heating equipment 10 of the present invention is operated on the frequency range greater than 5% bandwidth, so the microwave seal technology of using on conventional microwave oven proof is unsuitable for satisfying personnel's safety and to the requirement of Communication Jamming.
Figure 16 illustrates the front view of improved observation panel 92, and observation panel 92 is used for observing with eyes the situation of the sample in the microwave cavity 34.Observation panel 92 comprises " honeycomb " shape metallic filter 94, and the diameter of hexagonal cells is less than its degree of depth.For example, a kind of proper proportion is about 0.061 inch of diameter than thick 1.0 inches.This structure provides the decay of 250dB to the frequency of 20GHz at least at height.This filter 94 is arranged between the relative clear glass such as vitreosil etc., and the microwave that forms observation panel 92 seals.
Be necessary, seal 100, in Figure 17 A, made clearer diagram because the microwave on the chamber door 98 seals for personnel and communications protection so be provided with four layers of microwave as shown in figure 17 in the present invention.A pair of loop seal 102,104 stretches in the chamber 34, and ring 102 is connected on the door 98, encircles on 104 microwave ovens 32 that are connected in the chamber 34.Space between the ring 102,104 is used to disconnect waveguide, especially is being lower than on the frequency of 4GHz.Determined that suitable space is 0.06 inch.Support compressible 106 by the loop seal 103 that the microwave oven 32 in the chamber 34 bears, for example gold-plated copper sheet, in illustrated embodiment, it provides the decay of 70dB on the frequency of 10GHz.Loop seal 102 compressor bar 106 when door is closed that bears by door 98.Around around the door opening 112 that is supported on the chamber 34 being such as the monel net compressible 108, but it is as the door buffer of mild compression.The monel net 108 of present embodiment provides the decay of the 80dB that adds on the 10GHz frequency.And, be looped around on the chamber 34 compressible 108 be compressible 110, its forms the cross section that is essentially " e " shape.The compressor bar 110 of preferred embodiment is the silicones elastic strip of filling carbon, is used for the decay that frequency at 10GHz provides additional 75dB.The end product of this shielding when observation panel 92 and door 98 are closed be from variable frequency microwave heating apparatus, do not detect 2.4 and the frequency of 17.5GHz microwave leakage is arranged.Even the microwave leakage to lsafety level does not detect yet greatly.Person skilled in the art it should be understood that above-mentioned microwave seal structure according to be sealed and/or etc. the frequency range of shielding and the various combinations that power stage can be utilized described technology well.
Shown in Figure 18 is another embodiment of variable frequency microwave heating apparatus 10 of the present invention.In this embodiment, use microwave oscillator 14, the control 18 of prime amplifier power and the TWT20 that replaces previous embodiment such as the high power oscillator of the coaxial magnetron 114 of frequency sensitivity.The available bandwidth of the magnetron 114 of this preferred embodiment is at least 5% of its centre frequency.Magnetron 114 or manual FREQUENCY CONTROL are perhaps preferably carried out FREQUENCY CONTROL by closed loop, voltage base feedback control system.In this feedback control system, with the servomechanism in low level (0 to 10V) the signal excitation magnetron 114, make it accurately reset the plate in the coaxial cavity of magnetron (plunger plate) come from a frequency to another frequency ground " tuning " magnetron 114.
In order to determine the restriction factor of required bandwidth better, the rectangle microwave chamber 34 that constitutes 12 * 12 * 10 inches is desirable patterns, it be used for definite can be in chamber 34 on 4 to 6GHz frequency ranges supported resonance wave modulus.These result of calculations clearly prove, even in so little chamber 34, also even having a large amount of (surpassing 600), intensive mode (usually be on a frequency 3 to 4) on 4 to the 6GHz frequency ranges.These results have made diagram with mode density to the form of frequency in Figure 19.According to these results, significantly, in some cases, little 5% bandwidth to current frequency also can provide abundant mode, so that Energy distribution uniformly to be provided in microwave cavity 34.
With this desirable pattern, according to function calculation power density along the each point position on the horizontal midplane of microwave cavity.First kind of situation hypothesis centre frequency checking is 5GHz.As shown in FIG., along with the reduction of bandwidth percentage, it is inhomogeneous that distribute power little by little becomes, and wherein bandwidth is defined by the low-and high-frequency rate variance divided by centre frequency, perhaps:
(f
High-f
Low)/f
The center
Bandwidth is quite uniform greater than 10% power density approximately, and the uniformity of the power density of 5% bandwidth is poor slightly.Second kind of situation hypothesis centre frequency is 15GHz, drops to 1.3% the bandwidth power density of drawing corresponding to scope from 40%.In this case, for the bandwidth that is low to moderate 2.5%, compare with the previous case, power density is quite even.Even bandwidth only further is reduced to 1.3%, to use for many microwave heatings, power density is also enough even.
It is the power diagram that 5GHz does that Figure 20 A-D illustrates with above-mentioned idealized model and centre frequency.As used in the above-mentioned content, power diagram is a 3-D graphic, and it shows across the power on the each point of microwave cavity 34.Power is with z coordinate diagram, and x and y coordinate are the bottom surface of microwave cavity 34.The bandwidth of each figure is 5%, 10%, 20% and 40%.It should be noted that the increase along with bandwidth, microwave cavity 34 distribute power everywhere is more even.
Similarly, to illustrate with above-mentioned ideal and centre frequency be the power diagram that 15GHz does to Figure 21 A-F.Each bandwidth is 1.3%, 2.5%, 5%, 10%, 20% and 40%.Moreover, the bandwidth for 1.3%, distribute power between points changes significantly.Yet, basically level and smooth of the bandwidth for useful 40%, distribute power.
Used heat-sensitive paper at microwave cavity 34 build-in tests ideal results, proved precision, during test according to Utopian model selection microwave source 12.It is brown that focus or the position with high power distribution become heat-sensitive paper, and cold spot still makes heat-sensitive paper keep white.The result of these tests has confirmed the situation of hypothesis testing discussed above.
Though illustrated and described several preferred embodiments, and the several embodiment through constructing and estimating have been described particularly, but be to be understood that, these descriptions are not the restriction to disclosure, and in the spirit and scope that fall into the invention defined in appended claims or their equivalent all are modified and the method for conversion but covered.
Claims (33)
1, a kind of variable frequency microwave heating apparatus is used for the treatment of selected material, and described variable frequency microwave heating apparatus comprises microwave oven, and it is limited with a multimode chamber, is used to handle described selected material, it is characterized in that described variable frequency microwave heating apparatus comprises:
Microwave signal generator is used to produce the microwave of the useful wave band of an inswept appointment, and limits a centre frequency, and each described microwave limits a selected waveform, frequency and amplitude;
First signal amplifier, be used to amplify the described microwave that described signal generator produces, described first signal amplifier produces microwave in selected frequency range, and limit a centre frequency, the power of described microwave is relevant with selected amplitude, and described first signal amplifier includes the microwave electronic device that dedicated bandwidth is at least described centre frequency 5%;
Power supply is used for providing electric power to described first signal amplifier; With
Transmitter, the described microwave transmission that is used for described first signal amplifier is produced is in described microwave oven.
2, variable frequency microwave heating apparatus as claimed in claim 1 is characterized in that, described microwave electronic device is selected from following group: travelling wave tube, twystron, klystron, a crossing amplifier, coaxial magnetron and gyrotron.
3, variable frequency microwave heating apparatus as claimed in claim 1 is characterized in that, described power supply is adjustable, and the described amplitude of the described signal that can be selectively described signal generator be produced is modulated.
4, variable frequency microwave heating apparatus as claimed in claim 1 is characterized in that, further comprises the signal amplitude controller, is used for modulating selectively the described amplitude of the described signal that described signal generator produces.
5, variable frequency microwave heating apparatus as claimed in claim 1 is characterized in that, further comprises second amplifier, is used for amplifying selectively before described first amplifier described signal that described signal generator produces.
6, variable frequency microwave heating apparatus as claimed in claim 1 is characterized in that, further comprises:
The signal finder carries out orientation to the microwave of the described microwave of described first amplifier generation and the reflection of described microwave oven; With
The microwave reflection customer is used to consume from the described microwave of described microwave oven reflection, has its power and amplitude of being correlated with of institute from the microwave of described microwave oven reflection.
7, variable frequency microwave heating apparatus as claimed in claim 6 is characterized in that, described signal finder is provided with cooling device, is used to spread the heat that the work of described signal finder is gathered.
8, variable frequency microwave heating apparatus as claimed in claim 6, it is characterized in that, further comprise System Monitor, the described size of the described power that is used to monitor the described size of the described power relevant with the described microwave that sends described microwave oven to and is correlated with the described microwave that reflects from described microwave oven, described System Monitor is used to monitor the efficient of described variable frequency microwave heating apparatus.
9, variable frequency microwave heating apparatus as claimed in claim 1 is characterized in that, further comprises prime amplifier, and the microwave power that uses the selected driving stage of described signal generator to send described microwave cavity to reaches desired degree.
10, variable frequency microwave heating apparatus as claimed in claim 1, it is characterized in that, described transmitter comprises the waveguide applicator, it comprises by the waveguide that exports the inner wall limit of smooth convergent from entering the mouth to, so that at least 3: 1 free space voltage standing wave ratio to be provided on the useful band of described first signal amplifier.
11, variable frequency microwave heating apparatus as claimed in claim 10 is characterized in that, described waveguide applicator further comprises dielectric window, protects described variable frequency microwave heating apparatus when being used for being subjected in described multimode chamber being different from the pressure of ambient pressure.
12, variable frequency microwave heating apparatus as claimed in claim 11 is characterized in that, further comprises cooling device, is used to cool off described dielectric window.
13, variable frequency microwave heating apparatus as claimed in claim 11 is characterized in that, further comprises the tubular transition, to mate the impedance breakpoint between described waveguide and the described dielectric window.
14, variable frequency microwave heating apparatus as claimed in claim 1, it is characterized in that, described transmitter comprises the waveguide applicator, it comprises by the waveguide that exports the inner wall limit of step convergent from entering the mouth to, so that at least 3: 1 free space voltage standing wave ratio to be provided on the useful band of described first signal amplifier.
15, variable frequency microwave heating apparatus as claimed in claim 14 is characterized in that, described waveguide applicator further comprises dielectric window, protects described variable frequency microwave heating apparatus when being used for being subjected in described multimode chamber being different from the pressure of ambient pressure.
16, variable frequency microwave heating apparatus as claimed in claim 15 is characterized in that, further comprises cooling device, is used to cool off described dielectric window.
17, variable frequency microwave heating apparatus as claimed in claim 15 is characterized in that, further comprises the tubular transition, to mate the impedance breakpoint between described waveguide and the described dielectric window.
18, variable frequency microwave heating apparatus as claimed in claim 1, it is characterized in that, further comprise be oppositely arranged the door and seal, be used to prevent described microwave signal leakage, described surface has formed an opening, the described material of selecting is put into by this opening or is taken out from described multimode chamber, described sealing at least is made of a group of selecting from the following group that constitutes: be supported on described microwave cavity near and from described opening outward extending first the ring, support and big or small fitting by described door to be contained in second ring in described first ring, and be supported on compressible seal member between described first ring and described second ring, to seal when described ring encircles to form when holding by described first; At least one is supported and pad disposed thereon by described door, to make the described surface and the engagement of described around openings in described multimode chamber when described door is in the closed position; And at least one seals, and by the polymeric material manufacturing of compressible absorption microwave, and is supported by described door, is positioned on the described door, when described door is in the closed position the described surface in described multimode chamber and described around openings are meshed.
19, variable frequency microwave heating apparatus as claimed in claim 1 is characterized in that, described multimode chamber further comprises observation panel, is used for observing described selected material during handling, and described observation panel is equipped with micro-wave screening, leaks to prevent described microwave signal.
20, a kind of variable frequency microwave heating apparatus is used for the treatment of selected material, and described variable frequency microwave heating apparatus comprises microwave oven, and it is limited with a multimode chamber, is used to handle described selected material, it is characterized in that described variable frequency microwave heating apparatus comprises:
Microwave signal generator is used to produce the microwave of the useful wave band of an inswept appointment, and limits a centre frequency, and each described microwave limits a selected waveform, frequency and amplitude;
Power supply is used for providing electric power to described microwave signal generator;
Transmitter, the described microwave transmission that is used for described microwave signal generator is produced is in described microwave oven.
21, variable frequency microwave heating apparatus as claimed in claim 20 is characterized in that, the dedicated bandwidth that has of described coaxial magnetron is at least 5% of its centre frequency.
22, variable frequency microwave heating apparatus as claimed in claim 20 is characterized in that, described power supply is adjustable, and the described amplitude of the described signal that can be selectively described signal generator be produced is modulated.
23, variable frequency microwave heating apparatus as claimed in claim 20 is characterized in that, further comprises the signal frequency controller, is used to control the frequency of described coaxial magnetron vibration.
24, variable frequency microwave heating apparatus as claimed in claim 20, it is characterized in that, described transmitter comprises the waveguide applicator, it comprises by the waveguide that exports the inner wall limit of smooth convergent from entering the mouth to, so that at least 3: 1 free space voltage standing wave ratio to be provided on the useful band of described first signal amplifier.
25, variable frequency microwave heating apparatus as claimed in claim 24 is characterized in that, described waveguide applicator further comprises dielectric window, protects described variable frequency microwave heating apparatus when being used for being subjected in described multimode chamber being different from the pressure of ambient pressure.
26, variable frequency microwave heating apparatus as claimed in claim 25 is characterized in that, further comprises cooling device, is used to cool off described dielectric window.
27, variable frequency microwave heating apparatus as claimed in claim 25 is characterized in that, further comprises the tubular transition, to mate the impedance breakpoint between described waveguide and the described dielectric window.
28, variable frequency microwave heating apparatus as claimed in claim 20, it is characterized in that, described transmitter comprises the waveguide applicator, it comprises by the waveguide that exports the inner wall limit of step convergent from entering the mouth to, so that at least 3: 1 free space voltage standing wave ratio to be provided on the useful band of described first signal amplifier.
29, variable frequency microwave heating apparatus as claimed in claim 28 is characterized in that, described waveguide applicator further comprises dielectric window, protects described variable frequency microwave heating apparatus when being used for being subjected in described multimode chamber being different from the pressure of ambient pressure.
30, variable frequency microwave heating apparatus as claimed in claim 29 is characterized in that, further comprises cooling device, is used to cool off described dielectric window.
31, variable frequency microwave heating apparatus as claimed in claim 29 is characterized in that, further comprises the tubular transition, to mate the impedance breakpoint between described waveguide and the described dielectric window.
32, variable frequency microwave heating apparatus as claimed in claim 20, it is characterized in that, further comprise be oppositely arranged the door and seal, be used to prevent described microwave signal leakage, described surface has formed an opening, the described material of selecting is put into by this opening or is taken out from described multimode chamber, described sealing at least is made of a group of selecting from the following group that constitutes: be supported on described microwave cavity near and from described opening outward extending first the ring, support and big or small fitting by described door to be contained in second ring in described first ring, and be supported on compressible seal member between described first ring and described second ring, to seal when described ring encircles to form when holding by described first; At least one is supported and pad disposed thereon by described door, to make the described surface and the engagement of described around openings in described multimode chamber when described door is in the closed position; And at least one seals, and by the polymeric material manufacturing of compressible absorption microwave, and is supported by described door, is positioned on the described door, when described door is in the closed position the described surface in described multimode chamber and described around openings are meshed.
33, variable frequency microwave heating apparatus as claimed in claim 20 is characterized in that, described multimode chamber further comprises observation panel, is used for observing described selected material during handling, and described observation panel is equipped with micro-wave screening, leaks to prevent described microwave signal.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US22118894A | 1994-03-31 | 1994-03-31 | |
| US08/221,188 | 1994-03-31 |
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| CN1167562A CN1167562A (en) | 1997-12-10 |
| CN1148108C true CN1148108C (en) | 2004-04-28 |
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| Application Number | Title | Priority Date | Filing Date |
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| CNB951930621A Expired - Lifetime CN1148108C (en) | 1994-03-31 | 1995-03-30 | Variable frequency microwave heating apparatus |
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| EP (1) | EP0801879B1 (en) |
| JP (1) | JP3037433B2 (en) |
| KR (1) | KR100363603B1 (en) |
| CN (1) | CN1148108C (en) |
| AT (1) | ATE219321T1 (en) |
| AU (1) | AU695295B2 (en) |
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| CA1081796A (en) * | 1978-02-09 | 1980-07-15 | B. Alejandro Mackay | Controlled heating microwave ovens using different operating frequencies |
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| US5321222A (en) * | 1991-11-14 | 1994-06-14 | Martin Marietta Energy Systems, Inc. | Variable frequency microwave furnace system |
-
1995
- 1995-03-30 AU AU21957/95A patent/AU695295B2/en not_active Expired
- 1995-03-30 DE DE69527087T patent/DE69527087T2/en not_active Expired - Lifetime
- 1995-03-30 EP EP95914883A patent/EP0801879B1/en not_active Expired - Lifetime
- 1995-03-30 AT AT95914883T patent/ATE219321T1/en active
- 1995-03-30 JP JP07525779A patent/JP3037433B2/en not_active Expired - Lifetime
- 1995-03-30 CA CA002186882A patent/CA2186882C/en not_active Expired - Fee Related
- 1995-03-30 WO PCT/US1995/003757 patent/WO1995027387A1/en active IP Right Grant
- 1995-03-30 CN CNB951930621A patent/CN1148108C/en not_active Expired - Lifetime
- 1995-03-30 KR KR1019960705539A patent/KR100363603B1/en active IP Right Grant
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102149228A (en) * | 2010-02-08 | 2011-08-10 | 耀光联有限公司 | Microwave heater |
| WO2015161605A1 (en) * | 2014-04-24 | 2015-10-29 | 广东美的厨房电器制造有限公司 | Microwave oven |
Also Published As
| Publication number | Publication date |
|---|---|
| DE69527087T2 (en) | 2003-01-30 |
| EP0801879A4 (en) | 1998-01-07 |
| JPH09511355A (en) | 1997-11-11 |
| CA2186882A1 (en) | 1995-10-12 |
| JP3037433B2 (en) | 2000-04-24 |
| CA2186882C (en) | 2001-02-20 |
| WO1995027387A1 (en) | 1995-10-12 |
| EP0801879B1 (en) | 2002-06-12 |
| DE69527087D1 (en) | 2002-07-18 |
| KR100363603B1 (en) | 2003-03-03 |
| ATE219321T1 (en) | 2002-06-15 |
| AU2195795A (en) | 1995-10-23 |
| KR970702682A (en) | 1997-05-13 |
| EP0801879A1 (en) | 1997-10-22 |
| AU695295B2 (en) | 1998-08-13 |
| CN1167562A (en) | 1997-12-10 |
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